Cotton recycling

ABSTRACT

Cellulose materials and methods of making the cellulose materials are described herein. The method can include contacting a cotton fabric with an oxidizing system to obtain an oxidized cotton material and processing the oxidized cotton material to form the cellulose material. The oxidizing system can include an aqueous mixture of a N-oxyl compound and a hypochlorite compound. During oxidation, the pH of the aqueous mixture can be maintained at from 8.5 to 11. Cellulose products can be formed from the cellulose materials. For example, the cellulose products can be used to form a packaging material, a biomedical device or implant, a drug delivery material, a fiber, a textile material, a template for electronic components, or a separation membrane. Methods of making the cellulose product include dissolving or suspending an active ingredient in a medium comprising the cellulose material.

FIELD OF THE DISCLOSURE

This disclosure relates generally to recycling cotton fibers, moreparticularly, to recycling cotton fabrics to provide functionalcellulose materials.

BACKGROUND OF THE DISCLOSURE

Barrier properties of materials are important in reducing thepenetration of moisture, oxygen, grease, aromas and, in some cases,bacteria. For example, exclusion of oxygen and moisture from packagedfoods retards product spoilage. In certain applications, such aspackaging of detergents, cleaners, fertilizers and the like, it isimportant that the packaging material prevents the odors from spreadingoutside. In other applications, such as juices, wines, pretzels andbiscuits it is sought to protect the contents against acquisition ofundesirable flavors from the outside. Therefore, film structures whichprovide a barrier to oxygen, flavor/odor, grease/oil and moisture arehighly desirable food packaging materials.

There is an ongoing trend to coat paper products with metalized filmssuch as aluminum to provide moisture vapor and oxygen barrierprotection. However, while these films provide good barrier properties,they limit the recyclability of the paper product. Development oflow-carbon-footprint high barrier film materials in place of foil isincreasingly needed. To address this need, polymer-based film productssuch as ethylene vinyl alcohol, poly(vinyl) alcohol, and nylon preparedfrom m-xylene diamine are being used in today's food packaging market.These polymers possess high oxygen barrier properties but they have poormoisture barrier properties. In view of the foregoing limitations ofknown barrier films, there remains a need for barrier compositions whichexhibit sufficient barrier properties in reducing the penetration ofmoisture and oxygen. The compositions and methods disclosed hereinaddress these and other needs.

SUMMARY

Cellulose materials and methods of preparing the cellulose materials aredisclosed herein. The cellulose material can be derived from a cottonfiber such as a cotton fabric, including post-consumer waste cottonfabrics. The method of preparing the cellulose material can includecontacting the cotton fiber or fabric with an oxidizing system to obtainan oxidized cotton material. The cotton fabric may be decolored,mechanically shredded, milled, or a combination thereof, prior tocontacting it with the oxidizing system.

Any suitable oxidizing system can be used for oxidizing the cottonfiber. In some examples, the oxidizing system can include an N-oxylcompound. Exemplary N-oxyl compounds include2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO),4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-hydroxy TEMPO), a4-hydroxy TEMPO derivative obtained by etherification or esterificationof a hydroxyl group of 4-hydroxy TEMPO, a phthalimide-N-oxyl (PINO)radical, an aza-adamantane type nitroxy radical, or a mixture thereof.The oxidizing system can further include a secondary oxidant, such as ahypochlorite compound. In some embodiments, the oxidizing system caninclude an aqueous mixture of the N-oxyl compound and a hypochloritecompound. During oxidation of the cotton fiber, the pH of the aqueousmixture can be maintained at from 8.5 to 11, such as at pH 10.

The method of preparing the cellulose materials can include processingthe oxidized cotton material to form the cellulose material. Processingthe oxidized cotton material can include filtering, neutralizing,evaporating, distilling, rinsing, casting, extruding, spinning, or acombination thereof.

Cellulose products can be formed from the cellulose materials describedherein. For example, an active ingredient can be incorporated into thecellulose material to confer a suitable property to the cellulosematerial. In some examples, the cellulose product can be a packagingmaterial, a biomedical device or implant, a drug delivery material, afiber, a textile material, a template for electronic components, or aseparation membrane. Methods of preparing the cellulose product caninclude dissolving or suspending an active ingredient in the cellulosematerial to form the cellulose product. The active ingredient can beselected from an inorganic nanoparticle, a therapeutic agent, and acombination thereof. The active ingredient can be present in an amountof from 0.01% to 20% by weight, based on the weight of the celluloseproduct.

In some examples, the cellulose product can be a food packagingmaterial. The food packaging material can include the cellulose materialand a nanoparticle active ingredient. In some cases, the nanoparticleactive ingredient can exhibit moisture barrier properties, oxidationbarrier properties, or a combination thereof. Examples of suitablenanoparticle active ingredient can include a silicon oxide nanoparticle,a silver nanoparticle, a cerium oxide nanoparticle, a zinc oxidenanoparticle, a poly(vinyl) alcohol nanoparticle, or a combinationthereof. The food packaging material can have a moisture vaportransmission rate (MVTR) of 1.0 g/m² per 24 hours when measured at 38°C. and 90 RH %. Additionally, the food packaging material coated withthe cellulose product can have an oxygen transmission rate (OTR) of 10cm³/m² per 24 hours when measured at 23° C., 0% RH, and 1 atm.

In some examples, the cellulose product can be a textile material. Thetextile material can include the cellulose material and nanoparticlesthat can impart a functionality selected from insulating finishing,electrical conductivity, hydrophobic finishing, waterproof finishing,soil repellent finishing, fire resistance finishing, wrinkle freefinishing, anti-UV finishing, antimicrobial finishing, antistaticfinishing, coloration, reflective finishing, sunblock finishing,fragrance finishing, fabric softening finishing, anti-oxidant finishing,or combinations thereof. Examples of suitable nanoparticles for use inthe textile material can include nanoparticles as described herein, suchas a silicon oxide nanoparticle, a silver nanoparticle, a cerium oxidenanoparticle, a zinc oxide nanoparticle, a poly(vinyl) alcoholnanoparticle, or a combination thereof.

Cellulose articles can be prepared from the cellulose materialsdescribed herein. Methods for recovering a cellulose article from thecellulose material can include casting, extruding, or spinning thecellulose material to form the cellulose article.

DETAILED DESCRIPTION

Provided herein are compositions and articles comprising cellulosematerials. The compositions and articles comprising the cellulosematerials can also include an active ingredient. Methods of making andusing the compositions and articles are also described herein.

The compositions, articles, and methods described herein can beunderstood more readily by reference to the following detaileddescription of specific aspects of the disclosed subject matter and theExample included therein. However, before the present compositions andmethods are disclosed and described, it is to be understood that theaspects described below are not limited to specific synthetic methods orspecific reagents, as such may, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular aspects only and is not intended to be limiting.

General Definitions

In this specification and in the claims that follow, reference will bemade to a number of terms, which shall be defined to have the followingmeanings:

The term “fabric” as used herein refers to a web having a structure ofindividual fibers or threads which are interlaid by weaving (woven),knitting, braiding, or in an irregular, non-repetitive manner(non-woven). A nonwoven fabric or web can be formed from for example,melt-blowing processes, spun-bonding processes, and bonded carded webprocesses.

Throughout this specification the word “comprise” and other forms of theword, such as “comprising” and “comprises,” means including but notlimited to, and is not intended to exclude, for example, otheradditives, components, integers, or steps. The term “include” and otherforms of “include” has the same meaning as “comprise” and its otherforms.

The singular forms “a,” “an,” and “the” include plural referents unlessthe context clearly dictates otherwise. Thus, for example, reference to“a composition” includes mixtures of two or more such compositions andreference to “the compound” includes mixtures of two or more suchcompounds, and the like.

“Optional” or “optionally” means that the subsequently described eventor circumstance can or cannot occur, and that the description includesinstances where the event or circumstance occurs and instances where itdoes not.

A weight percent (wt %) of a component, unless specifically stated tothe contrary, is based on the total weight of the formulation orcomposition in which the component is included.

Reference will now be made in detail to specific aspects of thedisclosed materials, compounds, compositions, articles, and methods,examples of which are illustrated in the accompanying Example.

Compositions

Provided herein are compositions and articles comprising cellulosematerials. The cellulose materials can be derived from a natural cottonfiber or a cotton fabric. Cotton fabrics are known in the art and caninclude denim, terry, corduroy, flannel, canvas, and twill. In somecases, the cotton fabric can be derived from a pre-consumer orpost-consumer cotton waste such as jeans or towels. Pre-consumer jeansmanufacturing clippings or rags are available from the “jeans industry,”the jeans comprising long cotton fibers, the length of which are in therange of 20 to 50 mm and the fineness of which are in the range of 10 to20 μm.

The cellulose material can be formed into cellulose products. Thecellulose products can include the cellulose material and an activeingredient that confers a suitable property to the cellulose product.For example, the cellulose product can include an active ingredientselected from an inorganic nanoparticle, a therapeutic agent, or acombination thereof. In some embodiments, the cellulose product can be apackaging material, a biomedical device or implant, a drug deliverymaterial, a fiber, a textile material, a template for electroniccomponents, or a separation membrane.

The active ingredient can be present in the cellulose product in anamount of 0.01% or greater by weight of the cellulose product. Forexample, the cellulose product can comprise 0.1% or greater, 0.1% orgreater, 0.1% or greater, 0.2% or greater, 0.5% or greater, 1% orgreater, 1.5% or greater, 2% or greater, 3% or greater, 4% or greater,5% or greater, 6% or greater, 7% or greater, 8% or greater, 9% orgreater, 10% or greater, 12% or greater, 15% or greater, 20% or greater,or 25% or greater of the active ingredient, based on the weight of thecellulose product. In some examples, the cellulose product can comprise25% or less, 20% or less, 15% or less, 12% or less, 10% or less, 9% orless, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% orless, 2.5% or less, 2% or less, 1.5% or less, 1% or less, 0.5% or lessby weight active ingredient, based on the weight of the celluloseproduct. The amount of active ingredient in the cellulose product canrange from any of the minimum values described above to any of themaximum values described above. For example, the amount of activeingredient in the cellulose product can range from 0.01% to 25%, 0.01%to 20%, 0.01% to 15%, 0.01% to 10%, 0.01% to 5%, 0.5% to 10%, 0.5% to5%, 0.5% to 2.5%, 1% to 10%, or 1% to 5% by weight, based on the weightof the cellulose product.

Suitable examples of active ingredients useful in the cellulose productsdisclosed herein include an insulating material, an electricallyconductive material (such as an antistatic material), a hydrophobicmaterial, a fire retardant or suppressant, a water repellent material, asoil repellent material, a reflective material (such as a metallicreflector), a magnetic material, a thermochromic material, a bioactiveagent (such as an anti-microbial agent, anti-fungal agent, or an insectrepellent), a sunblock agent, a dye, a pigment, a fragrance, an insectrepellent, a fabric softener, an anti-wrinkle material, a UV-protectivematerial, an oxidation resistant material, or a combination thereof.

In some embodiments, the active ingredient can include a nanoparticle.The term “nanoparticle” as used herein, refers to any structure with oneor more nanosized features. A nanosized feature can be any feature withat least one dimension less than 1 μm in size. The nanoparticle can haveany of a wide variety of shapes including for example, spheroidal andelongated nanostructures. Thus, the term nanoparticle includesnanowires, nanotubes, spheroidal nanoparticles, and the like, orcombinations thereof. The nanoparticles used herein can have an averagediameter of 900 nanometers (nm) or less. In some embodiments, theaverage diameter of the nanoparticle can be 800 nm or less, 700 nm orless, 600 nm or less, 500 nm or less, 450 nm or less, 400 nm or less,350 nm or less, 300 nm or less, 250 nm or less, 200 nm or less, 150 nmor less, 100 nm or less, or 50 nm or less. In some embodiments, theaverage diameter of the nanoparticle can be 5 nm or greater, 50 nm orgreater, 100 nm or greater, 150 nm or greater, 200 nm or greater, 250 nmor greater, 300 nm or greater, 350 nm or greater, 400 nm or greater, 450nm or greater, 500 nm or greater, 600 nm or greater, 700 nm or greater,800 nm or greater, or 900 nm or greater. The average diameter of thenanoparticle can range from any of the minimum values described above toany of the maximum values described above. For example, the averagediameter of the nanoparticle can range from 5 nm to 700 nm, from 5 nm to500 nm, from 50 nm to 500 nm, or from 50 nm to 250 nm.

Examples of suitable nanoparticles for use in the cellulose product caninclude aluminum, iron, silver, cerium, zinc, gold, copper, cobalt,nickel, platinum, manganese, rhodium, ruthenium, palladium, titanium,vanadium, chromium, molybdenum, cadmium, mercury, calcium, zirconium,iridium, silicon, an oxide thereof, zeolite, graphite, carbon nanotubes,or a combination thereof. Specific examples can include silicon oxidenanoparticles, silver nanoparticles, cerium oxide nanoparticles, zincoxide nanoparticles, polyvinyl alcohol nanoparticles, or combinationsthereof. The nanoparticles described herein can be encapsulated withinthe cellulose material, dispersed throughout the cellulose material, orform a layer/coating on the cellulose material.

In some embodiments, the cellulose product can be a food packingmaterial. In these embodiments, a nanoparticle that can exhibit moisturebarrier properties, oxygen barrier properties, or a combination thereof,can be included in the cellulose material. In some examples, thecellulose product can be a textile material. The textile material caninclude any one of the active ingredients described herein.

Methods

Methods of making the cellulose materials and compositions containingthe cellulose materials are also described herein. As described herein,the cellulose material may be derived from a cotton fiber or cottonfabr100046ic. The method can include cutting, mechanically shredding,and/or milling the cotton fabric to provided finely divided cottonfabrics. Any suitable device can be used to cut, shred, and/or mill thecotton fabric.

The method of making the cellulose material can include contacting thecotton fabric with an oxidizing system to obtain an oxidized cottonmaterial. The oxidizing system can include an N-oxyl compound. SuitableN-oxyl compounds include 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO),4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-hydroxy TEMPO), a4-hydroxy TEMPO derivative obtained by etherification or esterificationof a hydroxyl group of 4-hydroxy TEMPO, a phthalimide-N-oxyl (PINO)radical, an aza-adamantane type nitroxy radical, or a mixture thereof.Other suitable N-oxyl compounds include4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy (4-oxo-TEMPO),4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO),4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl (4-acetamido-TEMPO),4-benzyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-benzyloxy-TEMPO),and 4-acetoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-acetoxy-TEMPO),4-phosphonooxy-TEMPO, N-hydroxybenzotriazole, or a mixture thereof.

The N-oxyl compound in the oxidizing system can be present in an amountof at least 0.1 mmol per gram of the cotton fabric. In some embodiments,the N-oxyl compound can be present in an amount of 0.15 mmol or greateror 0.2 mmol or greater per gram of the cotton fabric. In someembodiments, the N-oxyl compound can be present in an amount of 0.25mmol or less, 0.2 mmol or less, or 0.15 mmol or less per gram of thecotton fabric. In some embodiments, the N-oxyl compound can be presentin an amount of from 0.1 mmol to 0.25 mmol or from 0.15 mmol to 0.20mmol per gram of the cotton fabric. In some embodiments, the N-oxylcompound can be present in a catalytic amount for oxidation of thecotton fabric.

The oxidizing system can include a secondary oxidant. Suitable secondaryoxidants can include a hypochlorite compound such as sodium hypochloriteor tert-butyl hypochlorite, sodium chlorite, (diacetoxyiodo)benzene,meta-chloroperoxybenzoic acid, calcium chlorite, sodium bromite,chlorine, bromine, trichloroisocyanuric acid, or a combination thereof.

The secondary oxidant, such as sodium hypochlorite can be present in anamount of at least 3 mmol per gram of the cotton fabric. In someembodiments, the secondary oxidant can be present in an amount of 4 mmolor greater, 5 mmol or greater, 6 mmol or greater, 7 mmol or greater, 8mmol or greater, 9 mmol or greater, 10 mmol or greater, 15 mmol orgreater, or 20 mmol or greater per gram of the cotton fabric. In someembodiments, the secondary oxidant can be present in an amount of 25mmol or less, 20 mmol or less, 15 mmol or less, 10 mmol or less, 9 mmolor less, 8 mmol or less, 7 mmol or less, 6 mmol or less, 5 mmol or less,or 4 mmol or less per gram of the cotton fabric. In some embodiments,the secondary oxidant can be present in an amount of from 3 mmol to 25mmol or from 5 mmol to 15 mmol per gram of the cotton fabric.

In some embodiments, the oxidizing system can include an aqueous mixtureof the N-oxyl compound and the secondary oxidant. For example, theoxidizing system can include an aqueous mixture of 4-hydroxy TEMPO,sodium hypochlorite, and sodium bromide.

The cotton fabric can be present in an amount of 50% or less by weightof the aqueous mixture. For example, the cotton fabric can be present inan amount of 35% by less, 25% by less, 10% by less, 5% by less, 3% byless, or 2% by less by weight of the aqueous mixture.

Oxidation of the cotton fabric can be controlled by maintaining the pHof the aqueous mixture from 8.5 to 11. In some cases, the pH of theaqueous mixture can be maintained at 10. Any suitable compound can beused to adjust the pH of the aqueous mixture. In some embodiments, thepH can be adjusted using a base such as sodium hydroxide. Oxidation ofthe cotton fabric can also be controlled by heating the mixturecomprising the cotton fabric and the oxidizing system.

In some cases, the method can include decoloring the cotton fabric priorto contacting the fabric with the oxidizing system. For example, wherethe cotton fabric is a post-consumer waste, such as a jeans, the methodcan include decoloring the cotton fabric prior to oxidation. In someembodiments, the method does not include decoloring the cotton fabricprior to contacting the fabric with the oxidizing system. In theseembodiments, the cotton fabric can be decolored during oxidization ofthe cotton fabric.

Decoloring the cotton fabric can include contacting the cotton fabricwith an oxidizing or reducing agent. Suitable oxidizing agents fordecoloring the cotton fabric can include hypochlorite (for e.g. sodiumhypochlorite), peroxide (such as hydrogen peroxide or benzoyl peroxide),sodium chlorite, potassium permanganate, or ozone. Suitable reducingagents for decoloring the cotton fabric can include sulfur dioxide,thiourea dioxide, sodium hydrosulfite, sodium hydroxymethanesulfinate,zinc formaldehyde sulfoxylate, calcium formaldehyde sulfoxylate, sodiumsulfite, sodium bisulfite, and tin (II) chloride.

The oxidized cotton material can be processed to form the cellulosematerials described herein. Processing the oxidized cotton material caninclude filtering (for example to separate insoluble cotton fabric),neutralizing, evaporating, distilling, rinsing/washing, casting,extruding, spinning, or a combination thereof, the mixture comprisingthe oxidized cotton material. In some embodiments, processing theoxidized cotton material can include neutralizing the aqueous mixture toa pH of about 7. For example, the method can include rinsing theoxidized cotton material with a solvent, such as water until thefiltrate solution is neutral.

As described herein, the cellulose material can be used to form acellulose product. The method of forming the cellulose product caninclude dispersing, such as by homogenizing the cellulose material intoa medium comprising a solvent. The solvent can include be any suitablesolvent such as water, an alcohol, or an ionic liquid. Optionally, themedium can be filtered to remove insoluble fractions of cellulosematerial. The method can further include dissolving and/or suspendingone or more active ingredients in the medium comprising the cellulosematerial. The mixture of the cellulose material and active ingredientcan be homogenized to form a viscous mixture. The homogenized mixturecan be casted into a film by pouring into a container and drying at lowtemperature for example about 40° C. In some embodiments, the celluloseproduct can be obtained from extruding, spinning, or a combinationthereof. For example, a cellulose product can be prepared from aspinning process such as a gap/dry-wet spinning process or by a wet-wetspinning process.

As described herein, the cellulose product can be a food packingmaterial. The food packaging material can exhibit moisture barrier andoxygen barrier properties. The liquid-water and water-vapor resistanceof the food packaging material comprising the cellulose material can betested with the Cobb method, described by TAPPI T 441 (2001), which isincorporated by reference herein in its entirety. This method determinesthe amount of liquid water or moisture vapor absorbed by the cellulosematerial in a specified time under standardized conditions. In someembodiments, the food packaging product comprising the cellulosematerial described herein would pass the water resistance test set forthin this test method.

In some embodiments, the food packaging material comprising thecellulose material can exhibit a Cobb value of 0.01 g/m² to 25 g/m²(e.g., 25 g/m² or less, 20 g/m² or less, 15 g/m² or less, 10 g/m² orless, or 5 g/m² or less). In some embodiments, the food packagingmaterial can exhibit a moisture vapor transmission rate (MVTR) of 1 g/m²or less per 24 hours when measured at 38° C. and 90 RH %. For example,the food packaging material can exhibit a moisture vapor transmissionrate of 0.5 g/m² or less or 0.3 g/m² or less. In some embodiments, thefood packaging material comprising the cellulose material can exhibit anoxygen transmission rate (OTR) of 10 cm³/m² or less per 24 hours whenmeasured at 23° C., 0 RH %, and 1 atm. For example, the food packagingmaterial can exhibit an oxygen transmission rate of 8 cm³/m² or less, 6cm³/m² or less, 5 cm³/m² or less, 4 cm³/m² or less, 3 cm³/m² or less, 2cm³/m² or less, or 1 cm³/m² or less per 24 hours when measured at 23°C., 0 RH %, and 1 atm. The moisture vapor transmission rate (MVTR) canbe determined as described in ASTM E398, ASTM F1249 or TAPPI T448-M49.In some examples, the moisture vapor transmission rate (MVTR) can bedetermined as described in ASTM E398. The oxygen transmission rate (OTR)can be determined as described in ASTM D3985 or ASTM F1927. In someexamples, the oxygen transmission rate (OTR) can be determined asdescribed in ASTM D3985.

In some examples, the cellulose product can be a textile material. Thetextile material can include an active ingredient such that it canexhibit an insulating property, an electrically conductive property(such as an antistatic property), a hydrophobic property, a fireretardant or suppressant property, a water repellent property, a soilrepellent property, a reflective property, a magnetic property, athermochromic property, a bioactive property, a sunblock property, afragrance, an insect repellent property, a fabric softening property, ananti-wrinkle property, a UV-protective property, an oxidation resistantproperty, or a combination thereof. In some examples, the textilematerial can be thermally insulating. The basis weight of the textilematerial can be 20 g/m² or greater. For example, the basis weight of thetextile material can be 25 g/m² or greater, 30 g/m² or greater, 35 g/m²or greater, 40 g/m² or greater, 45 g/m² or greater, 50 g/m² or greater,55 g/m² or greater, 60 g/m² or greater, 65 g/m² or greater, 70 g/m² orgreater, 80 g/m² or greater, 90 g/m² or greater, 100 g/m² or greater,110 g/m² or greater, 140 g/m² or greater, 150 g/m² or greater, 170 g/m²or greater, 180 g/m² or greater, 190 g/m² or greater, or 200 g/m² orgreater. In some examples, the basis weight of the textile material canbe 200 g/m² or less. For example, the basis weight of the fabric can be190 g/m² or less, 180 g/m²or less, 160 g/m²or less, 150 g/m²or less, 130g/m² or less, 110 g/m²or less, 100 g/m²or less, 90 g/m² or less, 80g/m²or less, 70 g/m² or less, 65 g/m² or less, 60 g/m² or less, 55 g/m²or less, 50 g/m² or less, 45 g/m² or less, 40 g/m² or less, 35 g/m² orless, 30 g/m² or less, or 25 g/m² or less. The basis weight of thetextile material can range from any of the minimum values describedabove to any of the maximum values described above. For example, thebasis weight of the textile material can range from 25 g/m² to 200 g/m²,from 50 g/m² to 200 g/m², or from 50 g/m² to 170 g/m². The textilematerial can be made into textiles including jackets, coats, skirts,pants, suits, slacks, vests, gloves, and the like. The fabrics can alsobe made into use in non-apparel applications such as furniture andcarpets.

EXAMPLES Example 1: Preparation of Recycled Cotton Nanofiber Film

A piece of towel fabric (0.5 g) was cut, ground, and suspended in asolution system containing water (25mL), 4-hydroxyl-TEMPO (0.008 g, 0.04mmol), and sodium bromide (0.05 g, 0.5 mmol). TEMPO-mediated oxidationof the fabric slurry was started by adding 5% NaClO solution (10 mmol ofNaClO per gram of cellulose) dropwise with gentle agitation at roomtemperature. The oxidation was controlled by maintaining the pH value at10 by adding 0.5 M NaOH. When no more decrease in pH was observed, thereaction was taken as finished. The NaClO-oxidized cellulose (NOC) wasthoroughly washed with distill water until the filtrate solution wasneutral.

To make cellulose nanofibers, 0.2 g NOC was dispersed in 200 mL water(0.1 wt % of NOC concentrations) at room temperature and mechanicallyagitated for 10 minutes using a planetary mixer at a low rotation rate.The insoluble fractions were removed from the dispersion by filtration.The cellulose dispersion was homogenized for 3 h in the mixer with ahigh rotation rate to produce a viscous NOC nanofiber suspension, byadding 1 wt % SiO₂ nanoparticle. A NOC nanofiber film was formed by acasting method. The nano-dispersion was poured into a 4×4 inch plasticdish for drying for 24 h at 40° C.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present disclosurewithout departing from the scope or spirit of the invention. Otherembodiments of the disclosure will be apparent to those skilled in theart from consideration of the specification and practice of the methodsdisclosed herein. It is intended that the specification and examples beconsidered as exemplary only, with a true scope and spirit of theinvention being indicated by the following claims.

1. A cellulose material prepared by a process comprising: a. contacting a cotton fabric with an oxidizing system to obtain an oxidized cotton material; and b. processing the oxidized cotton material to form the cellulose material.
 2. The cellulose material of claim 1, wherein the cotton fabric is derived from a post-consumer cotton waste.
 3. The cellulose material of claim 1, wherein the oxidizing system comprises an N-oxyl compound.
 4. (canceled)
 5. The cellulose material of claim 3, wherein the oxidizing system comprises an aqueous mixture of the N-oxyl compound and a hypochlorite compound.
 6. (canceled)
 7. A cellulose product prepared from the cellulose material according to claim
 2. 8. (canceled)
 9. The cellulose product of claim 7, further comprising an active ingredient, wherein the active ingredient is selected from the group consisting of an inorganic nanoparticle, a therapeutic agent, and a combination thereof.
 10. The cellulose product of claim 8, wherein the active ingredient includes a nanoparticle having moisture barrier properties, oxidation barrier properties, or a combination thereof.
 11. The cellulose product of claim 9, wherein the active ingredient includes a silicon oxide nanoparticle, a silver nanoparticle, a cerium oxide nanoparticle, a zinc oxide nanoparticle a polyvinyl alcohol nanoparticle, or a combination thereof.
 12. The cellulose product of claim 9, wherein the active ingredient is present in an amount of from 0.01% to 20% by weight, based on the weight of the cellulose product.
 13. The cellulose product of claim 7, wherein the cellulose product is a packaging material, a biomedical device or implant, a drug delivery material, a fiber, a textile material, a template for electronic components, or a separation membrane.
 14. (canceled)
 15. (canceled)
 16. The cellulose product of claim 7, wherein the cellulose product is a textile material, wherein the textile material comprises nanoparticles dispersed throughout the textile that impart a functionality selected from insulating finishing, electrical conductivity, hydrophobic finishing, waterproof finishing, soil repellent finishing, fire resistance finishing, wrinkle free finishing, anti-UV finishing, antimicrobial finishing, antistatic finishing, coloration, reflective finishing, sunblock finishing, fragrance finishing, fabric softening finishing, anti-oxidant finishing, or combinations thereof.
 17. A method of making a cellulose material from a cotton fabric, the method comprising: a. contacting the cotton fabric with an oxidizing system to obtain an oxidized cotton material, and b. processing the oxidized cotton material to form the cellulose material.
 18. The method of claim 17, wherein the cotton fabric is derived from a post-consumer cotton waste.
 19. (canceled)
 20. The method of claim 17, wherein the oxidizing system comprises an N-oxyl compound.
 21. The method of claim 20, wherein the N-oxyl compound is selected from 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-hydroxy TEMPO), a 4-hydroxy TEMPO derivative obtained by etherification or esterification of a hydroxyl group of 4-hydroxy TEMPO, a phthalimide-N-oxyl (PINO) radical, an aza-adamantane type nitroxy radical, or a mixture thereof.
 22. The method of claim 20, wherein the oxidizing system comprises an aqueous mixture of the N-oxyl compound and a hypochlorite compound.
 23. The method of claim 22, wherein the pH of the aqueous mixture is maintained at from 8.5 to
 11. 24. The method of claim 18, further comprising decoloring the cotton fabric prior to the step of contacting the cotton fiber with an oxidizing system.
 25. The method of claim 17, wherein processing the oxidized cotton material comprises filtering, neutralizing, evaporating, distilling, rinsing, casting, extruding, spinning, or a combination thereof.
 26. (canceled)
 27. The method of 17, further comprises dissolving or suspending an active ingredient in the cellulose material, wherein the active ingredient is selected from an inorganic nanoparticle, a therapeutic agent, and a combination thereof.
 28. (canceled)
 29. (canceled)
 30. (canceled)
 31. (canceled)
 32. A method of making a cellulose product from a cotton fiber, the method comprising: a. contacting the cotton fiber with an oxidizing system to obtain an oxidized cotton material; b. recovering a cellulose material from the oxidized cotton material; and c. dissolving or suspending an active ingredient in the cellulose material to form the cellulose product.
 33. The method of claim 32, wherein the cotton fiber is derived from a post-consumer cotton waste.
 34. The method of claim 32, wherein the method further comprises step (e) casting, extruding, or spinning the cellulose product.
 35. (canceled) 